Method of treating glowers for electric lamps.



No. 722,701. PATENTED MAR. 17, 1903,

" M. W. HANKS.

I METHOD OF TREATING GLOWERS FOR ELECTRIC LAMPS.

APPLICATION FILED JUNE 13, 1901.

no MODEL.

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MARSHALL W. HANKS, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGE WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

METHOD OF TREATING GLOWERS FOR ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 722,701, dated March 17, 1903. Application liled June 18. 1901. Serial No. 64, 179. (No model.)

To all whom, it may concern.-

Be it known that I, MARSHALL W. HANKS, a citizen of. the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of Treating Glowers for Electric Lamps, of which the following is a specification.

My invention relates to the manufacture of electric-lamp glowers that are non-conductive when cold and conductive when hot; and it has for its object to provide an improved method for treating the glower-blanks for the purpose of shrinking them prior to the attachment of terminal wires thereto.

It has been the usual practice in the manufacture of glowers of the character above indicated to subject each glower-blank having a terminal wire attached to one end or a length of rod suitable for two glowers and having terminal wires permanently attached to both its ends to the action of current for suflicient length of time to shrink the blank, so thatit will undergo substantially no change during its term of active service in the lamp.

By mypresentinvention I propose to sh rink each glower-blank by the passage of current therethrough; but instead of utilizing terminal wires and solid contact-terminals for this purpose I propose to utilize an electric are as one of the terminals and a pair of tweezers or other suitable clamping device as the other terminal or to utilize two electric arcs as the terminals during the shrinking operation. In either case the heat of the electric are formed between the carbon electrodes will serve to raise the temperature of the blank to a point where it becomes conductive, provided the blank be of single-glower length and be held approximately vertical, and thereafter the current will pass between the arc and the clamping device or between the two arcs and through the blank, as the case may be, so long as the blank is supported in suitable position and until theshrinkage is completed. If the blank is of sufficient length to form two or more glowers or if it is held approximately horizontal,some source of heat other than the arc will generally be found necessary, or at least desirable, to heat the blank to conducting temperature. After the shrinkage is completed one of the arcs may be utilized for forming a bead on one end of the blank, to which the terminal wire may be affixed, and the blank then reversed and a bead formed on the other end, to which the other terminal wire may be affixed, thus completing the glower.

Referring now particularly to the drawings, in Fig. 1 the carbon electrodes or pencils 1, 2, and 3 are supplied with three-phase currents from a source 4-, which may be either a three-phase dynamo or the secondary of a transformer. Inasmuch as it is desirable to maintain a constant current in the arc-furnaces, I include in each conductor between each pencil or electrode and the source of current a steadying resistance 5, switches 6 being also shown for disconnecting the furnace from the source of current. The resistance 5 may be adjustable, if desired, in order to vary the current, and consequently the proportions, of the are produced between the electrodes 1, 2, and 3. The blank 7, from which the glower is to be formed, is shown as supported by means of a pair of tweezers 8, so that its lower end is located in the are for the purpose of shrinking the blank and also, if desired, the formation thereafter of a terminal head, to which a terminal wire may be attached. The tweezers are shown as connected to the conductor leading from the source of current to the electrode 1 and as having connected in series with it a steadying resistance 9. It will be observed that with this arrangement of apparatus the tweezers constitute one terminal for the blank and the arc constitutes the other terminal, so that when the blank is heated to conducting temperate re the current will flow through it for the length of time desired for shrinking purposes.

In Fig.2 the source of current is not shown; but the energy is single phase and is applied from conductors 10 and 11 to the carbon electrodes 12 and 13, the blank '7 being supported by a pair of tweezers 8, which are connected to the conductor 10 through a steadying resistance 9 in a manner similar to that already described in connection with Fig. 1. The conductor 10, leading to the electrodes 12, also contains a steadying resistance 14, these resistances being made adjustable, if desired.

With this arrangement the arc constitutes one terminal for the blank 7 when the temperature of the latter has been raised to the conducting-point, and the circuit during the time that the blank remains a conductor is from the conductor 10 through the steadying resistance 9, tweezers 8, blank 7, the arc and the electrode 13 to the conductor 11.

In Fig. 3 the several parts are the same in structure and mode of operation as those shown in Fig. 2, except that separate conductors leading from an independent source of energy are employed for shrinking the blank 7. This arrangement enables me to apply to the blank any desired amount of current at any desired voltage independently of the current and voltage producing the arc, and consequently makes it possible to shrink the blank more thoroughly than is the case where the current and voltage employed are the same as those producing the arc. The circuit 15 and 16 for producing the arc includes the steadying resistance 14 and the circuit 10 and 11 for the blank, and the connected elements 8 and 13 include a steadying resistance 9, the same as is indicated in Fig. 2.

In Fig. 4 I have shown two pairs of carbon electrodes 17 18 and 19 20, located such a distance from each other that a glower-blank 7 of the desired length may have its ends respectively in the two arcs, the blank being supported by a pair of tweezers 8 or by any other suitable means. The carbon electrodes are supplied with energy from a circuit 21 22, as follows: The upper carbon electrodes 17 and 18 are connected to the terminals of the secondary 23 of a transformer 24 through a suitable steadying resistance 25, the primary of the transformer being connected across the circuit 21 22. The lower electrodes 19 and are connected to the terminals of the secondary 26 of a transformer 27, the primary of which is also connected across the circuit 21 22, a suitable steadying resistance 28 being included in circuit with these electrodes and the transformer secondary. For the purpose of utilizing the two arcs as the terminals for the glower-blank in order to shrink the same I employ a third transformer 29, the primary of which is connected across the circuit 21 22 and the secondary30 of which has its terminals respectively connected to the electrodes 18 and 19, a steadying resistance 31 being also included in this circuit. It will be seen, therefore, that after the blank has been heated to conductivity the current will flow between the two arcs through the blank so long as it is held in suitable position therefor. If it is desired to use either of these arcs for forming beads upon the ends of the blank, the lower arc may be so adjusted as to be hotter than the other for that purpose, or the lower end of the blank may be projected into the center of the arc, and after the bead is formed and the terminal wire attached the blank may be reversed and the other end treated in the same manner. The beads may be simultaneously formed on both ends by means of the two arcs, provided the material of which the blank is composed and other conditions are such that both beads will maintain a substantially central position with reference to the axis of the blank.

It may be sometimes found necessary or desirable to heat the blanks to conducting temperature by means of a source of heat other than the are or arcs-such, for example, as a gas-flame-and I therefore desire it to be un derstood that my invention is not limited to any specific source of heat for the purpose indicated.

In each of the forms of apparatus illustrated it is of course possible to vary the amount of resistance in circuit, and though no specific means has been shown for this purpose the feasibility of adjusting or varying the amount of resistance in a circuit is so well known in the art that illustration thereof has been deemed unnecessary.

I do not desire to limit my invention to any specific apparatus or to all the steps herein described. My invention is therefore not to be considered as restricted except in so far as limitations may be expressed in the claims.

I claim as my invention- 1. The improvement in the art of making glowers which consists in subjecting a glowerblank to an are formed between a plurality of carbon electrodes to raise the blank to conducting temperature and passing current through the blank to shrink it, the are being utilized as one terminal for the blank during the shrinking operation.

2. The improvement in the art of making glowers which consists in subjecting a glowerblank to an electric are formed between a plurality of carbon electrodes to raise the blank to conducting temperature to form terminal beads on its ends and passing current through the blank to shrink it, the are being utilized as one of the terminals for the blank during all or a part of such operations.

3. The improvement in the art of making glowers which consists in supporting a glowerblank with its ends adjacent to or partially within two electric arcs formed between a plurality of electrodes, whereby said arcs constitute the terminals for said blank and a current flows through the latter and shrinks it.

4. The improvement in the art of making electric-lamp glowers which consists in simultaneously subjecting both ends of a glowerblank to electric arcs and at the same time passing current through the blank to shrink it.

5. The improvement in the art of making electric-lamp glowers which consists in simultaneously subjecting both ends of a glowerblank to electric arcs and utilizing said arcs as terminals whereby current is caused to traverse said blank to shrink it.

6. The improvement in the art of making electric-lamp glowers which consists in simultaneously subjecting both ends of a glowerblank to the action of electric arcs to raise it.

to conductingtemperature, to form beads on one or both of said ends, and passing current through the blank to shrink it, the arcs being utilized as terminals for said blank during all or a part of said steps.

7. The improvement in the art of making electric-lamp glowers which consists in subjecting one end of a glower-blank to an electric arc and passing an electric current through the glower to shrink it, the are being utilized as one of the terminals for the glower.

8. The improvement in the art of making electric-lamp glowers which consists in inserting one end of a glower-blank into an electric arc, utilizing said are as one terminal for the blank and passing an electric current through the blank to shrink it.

In testimony whereof I have hereunto subscribed my name this lst (lay of June, 1901.

MARSHALL WV. HANKS.

Witnesses:

JAMES B. YOUNG, WESLEY G. CARE. 

